Worried about my health

This month I had sex two times. The first time I bled a couple days later when I peed, but my trips to the bathroom got more frequent. I told my mom and she took me to the doctor. The doctor looked and the urine sample I had and told me I had a UTI. I got the medicine and everything was fine. after that I got my period. Then after I got my period I had sex with my boyfriend the second time this month and we had sex two times that night. I don't ever pee after sex but I was worried so just to make sure, I peed. The next day my boyfriend's mom took me home because I was in pain. I got in my shower and noticed that I was peeing blood again. I went back to the doctor and this time they tested my pee and I got the results back on Thursday. There was no sign of an infection found. life anyone knows what this could be please let me know asap.